JPS5856810B2 - Omnidirectional detection method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for detecting the direction of acting forces such as gravity and acceleration.

As can be seen from the fact that the attitude is generally expressed by two Euler angles (α, β), it is expressed by three parameters, but the direction can be expressed by two parameters, which has one degree of freedom less than the attitude.

In order to determine the values of these two parameters, which are the essential contents for direction detection, a method has been used so far in which each parameter is determined individually using mechanically independent devices.

For this reason, with conventional methods, (1) it is difficult to detect in all directions, (2) due to mechanical constraints, it is difficult to measure with high sensitivity in all measurement methods; (3)
Since the devices for detecting the two parameters are installed separately, it is difficult to downsize the entire detector (4).
) Since the directional deviation is detected by mechanical means that utilizes the deviation of the pendulum or the deflection of the beam, it has the disadvantage that it is difficult to measure the direction accurately.

The present invention has been made in view of these points, and it is an object of the present invention to provide an omnidirectional detection method and apparatus that solve the above-mentioned conventional drawbacks at once.

To explain the present invention, light from a light source is irradiated onto an opaque sphere that is installed in a transparent medium through which light travels linearly and whose position freely changes according to the direction of gravity or acceleration. This method is characterized by forming an image on a light-receiving surface through the light-receiving surface, and detecting the length and position of the image on the light-receiving surface.

Once the length and position information of the image is obtained, a desired solution, ie, direction, can be obtained using appropriate software or a system of mathematical formulas.

Further, the device is configured such that an opaque sphere is confined in a spherical cavity in a transparent plate-like medium together with a liquid having the same refractive index as the plate-like medium, and the opaque sphere can freely move.

As a result, the image created by the light from the light source on the two-dimensional light-receiving surface through the opaque sphere has information about the moving direction of the opaque sphere.

Therefore, the detector can be easily miniaturized, and since the opaque sphere can freely move inside the sphere container without being interfered with by anything, highly sensitive measurements in all directions are possible.

Furthermore, since it relies on optical means, it improves detection accuracy.
It can cause a person to die.

Hereinafter, the present invention will be explained based on Examples.

FIG. 1 is a block diagram of the equipment necessary to carry out the present invention.

A transparent plate-like medium 1 having a uniform refractive index has a spherical container 2 inside.

An opaque sphere 3 (the center of which is denoted by G) that does not transmit light is confined within this container.

Further, a space inside the container is filled with a transparent liquid medium 4 having the same refractive index as the plate-like medium 1.

Therefore, the opaque sphere 3 can freely roll and move inside the sphere container 2 (hereinafter simply referred to as movement).

). Moreover, the speed of the opaque sphere 3 at this time is set to an appropriate value by the action of the liquid medium 4.

With this mechanism, if the opaque sphere is, for example, a weight having its center of gravity at its center, it will move to the lowest position under the influence of gravity and become in an equilibrium state.

The spherical container 2 is irradiated with light emitted from a point light source on a line that passes through its center and is perpendicular to the plate surface of the plate-like medium 1. Therefore, the light that is not blocked by the opaque sphere 3 reaches the spherical container 2 as a point light source. center O
A two-dimensional light-receiving surface or area sensor S whose center is on a line connecting the
is input.

Here, the traveling direction of the light changes depending on the difference in the refractive index of the plate-like medium 1, the liquid medium 4, and the medium 5 surrounding the plate-like medium 1, but considering the case where the media 1 and 4 have the same refractive index. Therefore, light travels straight in the plate-like medium 1.

Therefore, the path of the light emitted from the point light source is expressed as shown in FIG. 1, and a groove is created on S that projects the outline of the opaque sphere 3.

This image is generally an ellipse, with light on the outside and dark on the inside.

In the ellipse created in this way, the present invention has a light-receiving surface S
The maximum distance Rd and the minimum distance R from the center O' to the ellipsoid
The direction in which the opaque sphere 3 exists is detected using data on the image position (Rdxo, Rdzo) on the light receiving surface of either one of ss and the light receiving surface that detects these.

It is clear that the image position at the minimum distance is in the opposite direction to the direction in which the maximum distance Rd is measured, and the three points, the maximum distance point, the center position O' on the light receiving surface, and the minimum distance point are lined up in a straight line. The sum of the distances is equal to the length of the major axis of the ellipse.

The reason why detection in all directions is possible will be explained below.

First, as a coordinate system necessary for proceeding with the geometric analysis, as shown in Figure 2, the direction from which the center O of the spherical container 2 is viewed from the point light source is the Y axis, and the center O of the spherical container 2 is and opaque sphere 3
The direction created by the line created by connecting the center G of (The closest direction is the Mo direction).

Further, as a coordinate axis related to the optical system, as shown in FIG. 2a, X is perpendicular to the Y axis.

Axis and Z.

Determine the two orthogonal axes of the axis. The direction in which the center G of the opaque sphere 3 is viewed from the point O is the Y axis and the X direction.

Let the angles deviating from the axis be α and β, respectively, and these 2
It is assumed that the direction in which the opaque sphere 3 exists is expressed using two rosettes.

Now, Rd, Rs and image position (R
α, using the three data (dxo, Rdzo)
Let's analyze how the value of β is determined.

In Fig. 2, the position on the light receiving surface (Rdxo, Rdzo
) The optical path that the light passing through the plate-like medium 1 and the medium 4 can be specifically shown as shown in FIG.

However, n14 represents the absolute refractive index of the plate-like medium 1 and the liquid medium 4, and n5 represents the absolute refractive index of the surrounding medium 5.

Also, ρ1 and ρ. are the incident angle and refraction angle when light enters the plate-like medium 1 from the surrounding medium 5, and ρ1 and ρt are the plate-like medium 1
The angle of incidence and angle of refraction when entering the surrounding medium 5 from

In such a case, the following relational expression holds. This is because the medium 1 is plate-shaped here.

Also, According to Snell's law becomes.

This can be obtained from equation (4), and by substituting equations (3) and (5) into equation (1), the following equation can be obtained.

By squaring both sides of equation (6) and rearranging, the following equation is obtained.

C1tan4ρ1+C2ta113ρ1+C3tan2
ρi Equation (7) above is a fourth-order algebraic equation with tanρ1 as an unknown, and if the maximum distance Rd or minimum distance Rs to the projected image is measured, using this equation, it can be determined that the rays touching the opaque sphere are transparent. It is possible to calculate the value of the incident angle ρi upon entering the plate-shaped medium 1, and to determine, from among several solution candidates, one that satisfies the following limiting conditions as the final solution for the incident angle ρi.

However, it is assumed that R2 x 2R3 and R5 x n14 hold true.

The upper and lower limits of ρi are respectively ρ.

−0, ρ1ρ.

This value is determined assuming that When the angle of incidence ρ1 on the plate-like medium 1 is determined, the inclination α (positive is adopted) of the ray l of the light ray that touches the opaque sphere 3 in FIG. 2 is determined as follows.

Also, the straight line l is the point ((W, -W3)tanρ1l-W3
), it can be expressed as the following equation.

Y-αX-α(W, -W3) tanρ1-w3 ++・
(10) The center G of the opaque sphere 3, which is in contact with the straight line Z, is on the straight line m, which is translated upward from the straight line 2 by b.

However, b is expressed as follows.

In other words, it lies on the straight line expressed by the following equation.

In addition, since the opaque sphere 3 is in contact with the inner wall of the spherical container in an equilibrium state, its center G has a radius (
There is also Tadochi in R2R3).

Therefore, the position of the center G of the opaque sphere 3 can be found by combining equations (12) and (13) as the intersection of the straight line and the circle.

In other words, by substituting Y in equation (12) into equation 03) and solving the following quadratic equation, we obtain Xl + X2(x s >
X2) is determined, and the result is substituted into formula 02) to obtain yl
, y2 are found.

In equation (14), if X has multiple plates, the solution (
XI+:! l'l ) into the following equation, the values of parameters α and β can be immediately obtained.

However, as shown in FIG. 2, the straight line m and the circle are generally connected to two points G1. Intersect at G2, (X, Y,) + (x2 + y
There are two sets of solutions for 2) (xl>x2).

Therefore, information Rs about the minimum distance to the projected image is used to determine which one should be adopted.

In other words, in equation (7), using Rs instead of Rd, the light rays touching the other side of the opaque sphere 3 are
Calculate and examine the angle of incidence.

Then, using the results, the plate-like medium 1 and the liquid medium 4 are
A straight line K representing the optical path inside is determined.

This straight line and the two points G1. The distance from G2 is R3
The one that gives the closest value to is the only solution to be found.

In this way, even if there are two solutions that satisfy equations (12) and (13), the truly necessary one can be drawn out of them, and the results can be used in equations (1, 51, and (16)). By applying this, the values of parameters α and β representing direction can be obtained.

Note that if X2 is negative, there is no need to examine the solution using R5, and 1. It is clear that (XI + Yl) is determined as the only solution.

As a result of the above analysis, the values of parameters α and β representing all directions are automatically determined based on the procedure shown in the following table.

Depending on the size relationship of the radii R2 and R3 of the ball control device 2 and the opaque sphere 3, the point 0' on the light receiving surface where the line connecting the point light source and the center of the ball control device intersects may not necessarily be included inside the projected image. do not have.

However, as shown in the analysis, the fact that O' is inside the projection image simplifies the procedure for determining the orientation.

To achieve this, each radius must be determined to satisfy R3 x R2 x 2R3.

The two-dimensional light-receiving surface can be intercepted by an area sensor using a solid-state image sensor or a photodiode array, and the output is processed by a microcontroller etc. to generate RdRs.
, (Rdxo, Rdzo), it is possible to automatically determine the values of parameters α and β representing the direction.

Furthermore, by placing a convex lens made of a medium with a larger refractive index than the surrounding medium 5 between the plate-like medium 1 and the light-receiving surface S, the spread of the light that projects the outline of the opaque sphere is suppressed, and the light-receiving surface It is possible to reduce the area.

The optical path in this case is shown in FIG.

Since the light ray that creates the real image of a point light source is a paraxial ray, the light that reaches the lens side through the plate-like medium 1 is an apparent point light source that is lifted from the actual point light source by a distance W7 expressed by the following formula. It is considered that the light is being emitted from L'.

Therefore, when the focal length of the lens 6 is F, the distance W7 from the lens center position to the real image L' is determined by the following equation.

Further, when the distance between the point on the lens through which the light ray touching the opaque sphere 3 passes and the center of the lens is defined as the maximum projection length Rd' on the light-receiving surface formed by passing through the H-lens, the following relationship holds true.

In equations (18), (19), and (20), H
When 2W3 is eliminated, the reduction rate μ of the projected length by the lens is expressed as follows.

From this equation, it is clear that the reduction ratio is uniquely determined by the position and focal length of the lens, regardless of the position of the opaque sphere 3 or the optical path.

Therefore, in omnidirectional detection when reducing the projected image of the opaque sphere 3 using a lens, the data of the projection length actually detected from the light receiving surface is simply multiplied by 1/μ. It would be a good idea to adopt the above-mentioned Rd and Rs.

Rdxo and Rd used in equation (■6) to determine the value of β
Regarding the value of zo, regardless of whether a lens is used or not, the position data of the point at which the distance to the projected image is the maximum can be used as is.

In the above explanation, as a procedure for detecting all directions,
In the first half, we have discussed a method of using the maximum distance Rd to the projected image, and in the second half, the minimum distance Rs, but conversely, a similar procedure can be considered in which Rs is used in the first half and Rd is used in the second half. .

In this case, it is clear that the image position where the distance to the projected image is the minimum value Rs is effective for determining the parameter β.

The point light source does not necessarily have to be placed outside the plate-like medium 1, but can also be placed inside the medium 1 or in close contact with the plate surface of the medium 1.

In this case, by setting Wl-W3, the previous considerations remain valid.

Furthermore, when the refractive index of the surrounding medium 5 is the same as that of the mediums 1 and 4 (R5-n14), the plate-like medium 1 is replaced only by the spherical container 2.

In this case, the light path emitted from the point light source, touching the opaque sphere, and reaching the light receiving surface is a straight line, and the incident angle ρ is calculated (
Since equation 7) is a linear equation with tanpi as an unknown, the value of ρi is uniquely determined, and the procedure for determining the values of parameters α and β is further simplified.

Light emitted from a point light source creates a projected image of an opaque sphere in any direction by irradiating the entire spherical container, but it is not necessarily necessary to irradiate the entire spherical container.

The reason for this is that by covering the outside of the opaque sphere with a transparent medium that has the same refractive index as medium 1, it is possible to limit the usable range of the effective incident angle ρi to below a specific value. It is.

In such a case, the part of the ball holder away from the straight line connecting the point light source with the center O of the ball container is not important as a path for light, so it may be transparent or have the same refractive index as the liquid medium 4. There is no need to do so, and the plate-like medium 1 and the spherical container 2 can be easily manufactured by using this part as a bonding point.

In carrying out the present invention, it is necessary that the plate-like medium 1 and the liquid medium 4 in the ball umpire are both transparent and have the same refractive index. Examples of such a medium include glass and tweed. (cedar) oil, etc.

The present invention houses a device for direction detection in a spherical container,
The opaque sphere is allowed to move freely within it, making it possible to detect in all directions.Moreover, it has the practical effect of always measuring the two parameters representing direction with maximum sensitivity, and making the entire device more compact. has.

Furthermore, since the information necessary for direction detection is obtained by optical means, it also has the effect of increasing detection sensitivity.

The present invention can be used in various ways depending on the factors that cause the opaque sphere to move, and detection of the direction of gravity can be cited as a representative example.

In other words, when the opaque ball is made to act as a weight with its center of gravity at its center, the opaque ball rolls on the inner wall of the ball umpire and comes to rest pointing in the direction of gravity, making it possible to detect the direction of gravity.

In short, the present invention places an opaque ball inside a transparent pitcher, irradiates the ball with light emitted from a point light source toward the pitcher, and uses the light-receiving surface perpendicular to the line connecting the point light source and the center of the ball container to Capture the projected image of an opaque sphere that moves freely within the sphere, and determine the maximum and minimum distances from the center position of the light-receiving surface to the image on the line connecting the point light source and the center of the spherical container, and the image of either of these detected. The two parameters representing the direction are determined by a certain procedure based on the three data of position, and by using a weight as an opaque sphere whose center of gravity is at the center, the direction of gravity or the acceleration of movement can be determined. It detects direction.

When controlling a robot's limbs, controlling not only the position but also the direction is very important.

However, there are currently no sensors suitable for detecting the direction of a robot's limbs, and the robot senses direction through complex matrix calculations using the control amount of each joint.

This method places a heavy burden on the computer and cannot be used to control limbs with high precision and speed.

The present invention solves this problem by providing a compact, high-performance omnidirectional detection method.

In particular, in the control of inverted pendulums and walking, it is thought to be highly effective not only in preventing vibration, rocking, and falling, but also in realizing dynamically stable control, and is effective from a practical standpoint. It's a very big useful thing.

[Brief explanation of drawings]

Fig. 1 shows an example of the configuration of an apparatus for carrying out the present invention, and Fig. 2 shows an optical system for obtaining a projected image, where a is a diagram of the image within the light-receiving surface, and b is a diagram perpendicular to the light-receiving surface, showing the pitcher and the opaque sphere. 3 is a geometrical optical path diagram, and FIG. 4 is an optical path diagram in a case where a lens is used to reduce the light-receiving surface area. In the figure, 1 is a transparent plate-shaped medium, 2 is a pitcher inside the plate-shaped medium 1, 3 is an opaque sphere, 4 is a transparent liquid filling the space inside the pitcher 2, and 5 is the periphery of the plate-shaped medium 1. medium, 6 is a convex lens,
α, β are parameters indicating the direction in which the ball mass moves, G
is the center and center of gravity of the opaque sphere 3, G7.
G2 is the intersection of the circle with radius (R2°R3) and the straight line m, H is the distance connecting the lens center and the position on the lens through which the rays touching the opaque sphere pass, L is the point light source, and L' is the plate-like medium 1 is the apparent point light source seen through 1, L" is the real image of the point light source L' by the lens, O is the center of the pitcher, O' is the center of the light receiving surface,
Pl is the X-axis component of the deviation of the light emitted from the point light source before it enters the medium 1, R2 is the deviation position with respect to the X-axis when the light passes through the medium 1, and P3 is the deviation from the medium 1. The X-axis component of the amount of deviation of the light until it reaches the light-receiving surface S, S is the light-receiving surface, R2 is the radius of the inner wall of the ball umpire 2, and R3 is the opaque sphere 3
Rd is the maximum distance from the center O' of the light-receiving surface S to the projected image, Rd' is the maximum distance of the image formed on the light-receiving surface S when a lens is used, and Rs is the light-receiving element that detects the maximum distance Rs. The distance to the image in the opposite direction to the position, Rdxo
is the X of Rd. The axis component, Rd zo is the Z of Rd. Axis component, Z is the position on the light receiving surface (Rdxo + Rdzo)
m is the straight line representing the locus of movement of the center position of the opaque sphere 3, k is the optical path within the plate-like medium 1 that illuminates the minimum distance image position, ρi and ρ. are the incident angle and refraction angle when light enters medium 1 from medium 5, ρ1' and 0g are the incidence angle and refraction angle when light enters medium 5 from medium 1, and n14 is the line pair of media 1 and 4. The refractive index n5 is the absolute refractive index of medium 5, Wl is the distance between point O and the point light source, W2 is the distance between point O and point 07, and W3 is the distance between the plane of incidence of light into medium 1 and point 0. , W4 is the distance between the surface from which light emerges from medium 1 and point 0, W5 is the distance from point O to the lens surface, W3 is the distance from the point light source imaging position L" to the lens surface, and W7 is the lens side. The distance between the apparent point light source and the actual point light source when looking at the point light source from Each represents a system.

Claims (1)

[Claims] 1. An opaque sphere that moves according to the direction of the acting force is confined in a transparent spherical cavity, and at least the opaque sphere is irradiated with light from a light source, and two-dimensional light is received through the opaque sphere. An omnidirectional detection method characterized in that the moving direction of the opaque sphere is detected by detecting the length and position of a groove formed on a surface. 2. A transparent plate-like medium having a spherical cavity, a transparent liquid having the same refractive index as the plate-like medium within the spherical cavity, and an opaque sphere containing the liquid within the spherical cavity. and a light source for irradiating at least the opaque sphere with light, and a two-dimensional light-receiving surface for creating an image of the opaque sphere;
An omnidirectional detection device comprising photoelectric conversion detection means provided on the two-dimensional light receiving surface for detecting the length and position of the image, and detecting the moving direction of the opaque sphere. 3. The omnidirectional detection device according to claim 2, which employs a weight whose center of gravity is at the center as an opaque sphere, and detects the direction of gravity or the direction of acceleration.